Muscles of the Arm and Hand

Flexor Digitorum Superficialis Muscle

A large muscle that runs along the bottom of the forearm from all the bones at the elbow to the four fingers. It serves to flex or curl the fingers. A flexor muscle is one that decreases the angle between two bones, as in bending the arm at the elbow; raising the leg toward the stomach as in kicking a football; or bringing the lower leg up toward the thigh.

Extensor Digiti Minimi Muscle

A long, thin muscle of the forearm that arises from the humerus bone and inserts with the little finger's extensor expansion. It serves to straighten the little or pinkie finger. Muscle extension occurs when the angle between the bones is increased - as when the forearm is aligned with the arm

Flexor Digiti Minimi Brevis Muscle of Hand

A short muscle arising from the hamate bone of the wrist and inserting on the phalanx of the little finger, serving to flex that finger. A flexor muscle is one that decreases the angle between two bones, as in bending the arm at the elbow; raising the leg toward the stomach as in kicking a football; or bringing the lower leg up toward the thigh.

Pronator Teres Muscle

A short muscle connecting the ends of the humerus (upper arm bone) and ulna to the radius (forearm bones). It functions to rotate the arm toward the inside, as when the hand is turned so the palm is facing downward (pronation).

Extensor Pollicis Brevis Muscle

A short muscle originating from the radius to insert on the thumb and serves to straighten it out. Muscle extension occurs when the angle between the bones is increased - as when the forearm is aligned with the arm. An extensor, then, is any muscle serving to extend a bodily part (usually a limb) away from the body or when a digit is extended from its base.

Supinator Muscle

A short muscle whose fibers run from the ulna (long forearm bone) and the lateral end of the humerus (upper arm bone) to the radius (short forearm bone). It assists the biceps brachii in rotating the forearm laterally (supination).

Teres Major Muscle

A thick, flattened muscle that brings the arm toward the body and assists in extending it when the arm is in a flexed position. There are two teres muscles. The other one is the teres minor muscle, which rotates the arm laterally and assists in bringing it toward the body. As it draws the upper arm bone (humerus) up, it strengthens the shoulder joint.

Palmar Interosseous Muscles

Adductors of the digits in the hand.

Flexor Carpi Radialis Muscle

An extrinsic muscle of the hand found on the ulnar side of the forearm. It arises from the medial epicondyle, medial olecranon, and proximal ulnar head at the elbow to insert on several of the carpal bones. It serves to flex the wrist (move it toward the anterior forearm) and adduct the wrist.

Flexor Carpi Ulnaris Muscle

An extrinsic muscle of the hand found on the ulnar side of the forearm. It arises from the medial epicondyle, medial olecranon, and proximal ulnar head at the elbow to insert on several of the carpal bones. It serves to flex the wrist (move it toward the anterior forearm) and adduct the wrist.

Extensor Retinaculum of Hand

Consists of a group of heavy connective fibers in the tissues of the wrist. It connects the lateral margin of the radius (shorter forearm bone) with the inside border of the ulna (longer forearm bone) and with certain bones of the wrist.

Flexor Retinaculum of Hand

Consists of a group of heavy connective fibers in the tissues of the wrist. It connects the lateral margin of the radius (shorter forearm bone) with the inside border of the ulna (longer forearm bone) and with certain bones of the wrist.

Opponens Pollicis Muscle

Flexes and adducts the thumb.

Lumbrical Muscles of Hand

Four small, fleshy muscles that are associated with tendons between the four fingers of the hand. Each lumbrical muscle flexes the corresponding digital joint to extend the finger in question.

Extensor Carpi Ulnaris Muscle

Located along the outer surface of the ulna (longer forearm bone) and connects the humerus (upper arm bone) to the hand. It acts to extend the wrist and assists in abducting it.

Supraspinatus Muscle

Located in the depression above the spine of the scapula (shoulder blade) on the back surface. It connects the scapula to the greater tubercle of the humerus (upper arm bone) and acts to abduct the upper arm.

Palmaris Longus Muscle

One of the most variable muscles in the body and is sometimes (10% of the time) absent. It may be mostly tendon near the point of attachment and muscular at the far end, or it may be muscular in the center with tendons above and below. It may have two bundles of muscle with a central tendon, or it may be made up of a tendinous band, or the muscle make-up may be doubled.

Subscapularis Muscle

One of the rotator cuff muscles. The stability of the shoulder joint is mainly provided by the tendons of the subscapularis, teres minor, infraspinatus, and supraspinatus muscles that together form the rotator cuff. The cuff is fused to the underlying joint capsule except inferiorly.

Teres Minor Muscle

Rotates the arm laterally and assists in bringing it toward the body. As it draws the upper arm bone (humerus) up, it strengthens the shoulder joint. There are two teres muscles. The other one is the teres major muscle, a thick, flattened muscle that brings the arm toward the body and assists in extending it when the arm is in a flexed position.

Pronator Quadratus Muscle

Runs from the far end of the ulna (longest forearm bone) to the far end of the radius (shortest forearm bone). It assists the pronator teres in rotating the arm toward the inside, as when the hand is turned so the palm is facing downward.

Anconeus Muscle

The anconeus muscle is a small, triangular muscle that lies on the elbow joint and appears to be a continuation of the triceps brachii. It assists in extending the forearm and is supplied by a branch of the radial nerve.

Brachialis Muscle

The brachialis muscle is a large muscle beneath the biceps brachii. It connects the shaft of the humerus (upper arm bone) to the ulna (longest forearm bone) and is the strongest flexor of the elbow.

Brachioradialis Muscle

The brachioradialis muscle connects the humerus (upper arm bone) to the radius (shortest lower arm bone) and aids in flexing the elbow.

Coracobrachialis Muscle

The coracobrachialis muscle originates from the coracoid process of the scapula, inserts on the middle, inner border of the humerus and functions to raise and adduct arm.

Deltoid Muscle

The deltoid muscle is a rounded, triangular muscle located on the uppermost part of the arm and the top of the shoulder. It is named after the Greek letter delta, which is shaped like an equilateral triangle. The deltoid is attached by tendons to the skeleton at the clavicle (collarbone), scapula (shoulder blade), and humerus (upper arm bone). The deltoid is widest at the top of the shoulder and narrows to its apex as it travels down the arm. Contraction of the deltoid muscle results in a wide range of movement of the arm at the shoulder due to its location and the wide separation of its muscle fibers.

Extensor Carpi Radialis Brevis Muscle

The extensor carpi radialis brevis is a companion of the extensor carpi radialis longus and extends toward the middle of it. This muscle runs from the humerus (upper arm bone) to the bones in the hand and functions to extend the wrist. It also assists in abducting the hand.

Extensor Digitorum Muscle

The extensor digitorum muscle is an extrinsic muscle of the hand that originates at the lateral epicondyle in the elbow. The muscle crosses the posterior forearm to insert on the posterior of the phalanges, serving to extend the fingers and the wrist.

Flexor Digitorum Profundus Muscle

The flexor digitorum profundus muscle is a large muscle that connects the ulna (longest forearm bone) to the bones of the fingers. It acts to flex the distal joints of the fingers, as when a fist is made.

Flexor Pollicis Brevis Muscle

The flexor pollicis brevis muscle is a short muscle that runs from the wrist to the proximal phalanx of the thumb to bend the thumb toward the palm. A flexor muscle is one that decreases the angle between two bones, as in bending the arm at the elbow; raising the leg toward the stomach as in kicking a football; or bringing the lower leg up toward the thigh.

Infraspinatus Muscle

The infraspinatus muscle is one of the rotator cuff muscles. The stability of the shoulder joint is mainly provided by the tendons of the subscapularis, teres minor, infraspinatus, and supraspinatus muscles that together form the rotator cuff.

Biceps Brachii Muscle (Long Head)

The long head of the biceps brachii muscle is the larger of the two muscle bodies that forms the entire biceps brachii muscle. The biceps brachii gets its name from the Latin words for "two-headed" and "arm" which describe its structure and location. The long and short heads of the biceps brachii work together to achieve the same functions.

Biceps Brachii Muscle (Short Head)

The short head of the biceps brachii is the shorter and medial of the two bodies that form the biceps brachii muscle in the upper arm. Like the long head of the biceps brachii, the short head is a flexor and supinator of the elbow joint. At the shoulder joint, the short head aids in adduction of the humerus.

Triceps Brachii Muscle (Lateral Head)

Triceps brachii muscle is a muscle of the back of the arm, originating from the back of the humeral shaft and inserting at the elbow. The triceps brachii has three heads (connective immovable muscle) and is the only muscle on the back of the upper arm.

Triceps Brachii Muscle (Long Head)

Triceps brachii muscle is a muscle of the back of the arm, originating from the scapula and shoulder to insert at the elbow. The triceps brachii has three heads (connective immovable muscle) and is the only muscle on the back of the upper arm.

Triceps Brachii Muscle (Medial Head)

Triceps brachii muscle is one head of the triceps muscle and originates from the back of the humerus. The triceps brachii has three such heads (connective immovable muscle) and is the only muscle on the back of the upper arm.